This invention relates generally to anti-data pirating technology. More specifically, the invention relates to data disc modulation for preventing piracy and/or unauthorized access and/or unauthorized copying of data, such as audio and/or video data from a data source, such as compact discs (CDs), digital versatile discs, (DVDs), hard drive discs, an Internet Service Provider (ISP) data source, and other data discs and/or data sources via direct connection, or via a local and/or global network, such as the Internet.
There are two basic methods for recording sound and musicxe2x80x94analog and digital. See e.g. Ken C. Pohlmann, xe2x80x9cThe Compact Discxe2x80x9d, THE COMPUTER MUSIC and DIGITAL AUDIO SERIES, Volume 5. The above-mentioned audio series, which was published by A-R Editions, Inc., in Madison, Wis., is, along with all volumes therein, incorporated by reference.
In analog recording, the recording medium (a tape) varies continuously according to the sound signal. In other words, an analog tape stores sound signals as a continuous stream of magnetism. The magnetism, which may have any value within a limited range, varies by the same amount as the sound signal voltage.
In digital recording, the sound signal is sampled electronically and recorded as a rapid sequence of separately coded measurements. In other words, a digital recording comprises rapid measurements of a sound signal in the form of on-off binary codes represented by ones and zeros. In this digital system, zeros are represented by indentations or pits in a disc surface, and ones are represented by unpitted surfaces or land reflections of the disc, such that a compact disc contains a spiral track of binary codes in the form of sequences of minute pits produced by a laser beam.
Music that is input to a digital recording and the requisite series of reproduction processes, must pass through the recording side of a pulse code modulation (PCM) system. A master recording of the music is stored in digital form on a magnetic tape or optical disc. Once the magnetic tape has been recorded, mixed and edited, it is ready for reproduction as a CD. The CD manufacturer then converts the master tape to a master disc, which is replicated to produce a desired number of CDs. At the end of the PCM system is the reproduction side, the CD player, which outputs the pre-recorded music.
If digital technology is used in all intermediate steps between the recording and reproduction sides of the PCM system, music remains in binary code throughout the entire chain; music is converted to binary code when it enters the recording studio, and stays in binary code until it is converted back to analog form when it leaves the CD player and is audible to the listener. In most CD players, digital outputs therefrom preserve data in its original form until the data reaches the power amplifier, and the identical audio information recorded in the studio is thereby preserved on the disc.
The physical specifications for a compact disc system are shown in Prior Art FIG. 1. They were developed jointly by Sony and Philips, and are defined in the standards document entitled Red Book, which is incorporated herein by reference. The CD standard is also contained in the International Electrotechnical Commission standard entitled, Compact Disc Digital Audio System, also incorporated herein by reference. Disc manufacturers, as well as CD player manufacturers, must obtain a CD license to use these specifications.
All disc dimensions, including those pertaining to pit and physical formations, which encode data, are defined in the CD standard. For example, specifications information on sampling frequency, quantization word length, data rate, error correction code, and modulation scheme are all defined in the standard. Properties of the optical system that reads data from the disc using a leaser beam are also defined in the standard. Moreover, basis specifications relevant to CD player design is located in the signal format specifications.
Referring to Prior Art FIG. 2, the physical characteristics of the compact disc surface structure are described. Each CD is less than 5 inches in diameter whose track thickness is essentially thinner than a hair and whose track length averages approximately 3 and a half miles. The innermost portion of the disc is a hole, with a diameter of 15 mm, that does not hold data. The hole provides a clamping area for the CD player to hold the CD firmly to the spindle motor shaft.
Data is recorded on a surface area of the disc that is 35.5 mm wide. A lead-in area rings the innermost data area, and a lead-out area rings the outermost area. Both lead-in and lead-out areas contain non-audio data used to control the CD player. Generally, a change in appearance in the reflective data surface of a disc marks the end of musical information.
A transparent plastic substrate comprises most of the CD""s 1.2 mm thickness. Viewing a magnified portion of the CD surface, as shown in Prior Art FIG. 2, the top surface of the CD is covered with a very thin metal layer of generally aluminum, silver or gold. Data is physically contained in pits impressed along the CD""s top surface. Above this metalized pit surface and disc substrate lies another thin protective lacquer coating (10 to 30 micrometers). An identifying label (5 micrometers) is printed on top of the lacquer coating.
A system of mirrors and lenses sends a beam of laser light to read the data. A laser beam is applied to the underside of a CD and passes through the transparent substrate and back again. The beam is focused on the metalized data surface that is sandwiched or embedded inside the disc. As the disc rotates, the laser beam moves across the disc from the center to the edge. This beam produces on-off code signals that are converted into, for example, a stereo electric signal.
Prior Art FIG. 3 shows a typical compact disc pit surface. Each CD contains a track of pits arranged in a continuous spiral that runs from the inner circumference to the outer edge. The starting point begins at the inner circumference because, in some manufacturing processes, tracks at the outer diameter of a CD are more generally prone to manufacturing defects. Therefore, CDs with shorter playing time provide a greater manufacturing yield, which has led to adoption of smaller diameter discs (such as 8 cm CD-3 discs) or larger diameter discs (such as 20 and 30 cm CD-Video discs).
Prior Art FIG. 4 shows a diagram of a typical track pitch. The distance between successive tracks is 1.6 micrometers. That adds up to approximately 600 tracks per millimeter. There are 22,188 revolutions across a disc""s entire signal surface of 35.5 millimeters. Hence, a pit track may contain 3 billion pits. Because CDs are constructed in a diffraction-limited mannerxe2x80x94creating the smallest formations of the wave nature of lightxe2x80x94track pitch acts as a diffraction grating; namely, by producing a rainbow of colors. In fact, CD pits are among the smallest of all manufactured formations.
The linear dimensions of each track on a CD is the same, from the beginning of a spiral to the end. Consequently, each CD must rotate with constant linear velocity, a condition whereby uniform relative velocity is maintained between the CD and the pickup.
To accomplish this, the rotational speed of a CD varies depending on the position of the pickup. The disc rotates at a playing speed which varies from 500 revolutions per minute at the center, where the track starts, to 200 revolutions per minute at the edge. This difference in speed is accounted for by the number of tracks at each position.
For example, because each outer track revolution contains more pits than each inner track revolution, the CD must be slowed down as it plays in order to maintain a constant rate of data. So, when the pickup is reading the inner circumference of the CD, the disc rotates at the higher speed of 500 rpm. And as the pickup moves outwardly towards the disc""s edge, the rotational speed gradually decreases to 200 rpm. Thus, a constant linear velocity is maintained, such that all of the pits are read at the same speed. The CD player constantly reads from synchronization words from the data and adjusts the disc speed to keep the data rate constant.
A CD""s constant linear velocity (CLV) system is significantly different from an LP""s system. A major difference stems from the fact that a turntable""s motor rotates at a constant velocity rate of 33⅓ grooves. This translates into outer grooves having a greater apparent velocity than inner grooves, probably explained by the occurrence that high-frequency responses of inner grooves is inferior to that of outer grooves. If a CD used constant angular velocity (CAV) as opposed to the CLV system, pits on the outside diameter would have to be longer than pits on the inner diameter of the disc. This latter scenario would result in decreased data density and decreased playing time of a CD.
Like constant linear velocity, light beam modulation is also important to the optical read-out system that decodes the tracks. See Prior Art FIG. 5. A brief theoretical discussion on the distinctions between pit and land light travel explains this point.
Generally, when light passes from one medium to another with a different index of refraction, the light bends and its wavelength changes. The velocity at which light passes is important, because when velocity is slow, the beam bends and focusing occurs. Owing to several factors, such as the refractive index, disc thickness and laser lens aperture, the laser beam""s size on the disc surface is approximately 800 xcexcm. However, the laser beam is focused to approximately 1.7 xcexcm at the pit surface. In other words, the laser beam is focused to a point that is a little larger than a pit width. This condition minimizes the effects of dust or scratches on the CD""s outer surface, because the size of dust particles or scratches are effectively reduced along with the laser beam. Any obstruction less than 0.5 ml are essentially insignificant and causes no error in the readout.
As previously noted, a CD""s entire pit surface is metalized. In addition, the reflective flat surface between each pit,(i.e. a land), causes almost 90 percent of laser light to be reflected back into the pickup. Looking at a spiral track from a laser""s perspective on the underside of a disc, as shown in Prior Art FIG. 5, pits appears as bumps. The height of each bump is generally between 0.11 and 0.13 xcexcm, such that this dimension is smaller than the laser beam""s wavelength (780 nanometers) in air. The dimension of the laser beam""s wavelength in air is larger than the laser""s wavelength (500 nanometers) inside the disc substrate, with a refractive index of 1.55. In short, the height of each bump is, therefore, one-quarter of the laser""s wavelength in the substrate.
Scientifically, this means that light striking a land will travel twice as far than light striking a bump. This discrepancy in light travel distances serve to modulate the intensity of a light beam. This allows data physically encoded on the disc to be recoverable by the laser.
Also, the pits and intervening reflective lands on the disc""s surface do not directly designate ones and zeros. Rather, it is each pit""s edge, whether leading or trailing, that is a 1 and all areas in between, whether inside or outside a pit, that are designated as zeros. Still, each pit and reflective land lengths vary incrementally. The combinations of 9 different pit and land lengths of varying dimensions physically encode the data.
Error correction is one of the major advantages of digital audio storage media, such as compact discs, over analog media, like LPS. Error correction simply corrects the error.
When an LP is scratched, for instance, the grooves are irrevocably damaged, along with the information contained in them. On every replay of that record, there will be a click or pop when the damaged part of the groove passes beneath the needle.
This is not the case for CDs. The data on every disc is specially encoded with an error correction code. When a scratched CD is played, the CD player uses the error correction code to perform error correction every time the disc is played. Thus, it delivers the original undamaged data, instead of the damaged data.
The CD player contains two primary systems: an audio data processing system and a control system. Prior Art FIG. 6 depicts a block diagram of a CD player showing an audio path as well as servo and control functions. Generally, the data path, which directs modulated light from the pickup through a series of processing circuits, consists of several elements that ultimately produces a stereo analog signal. These elements of the data path include a data separator, buffer, de-interleaving RAM, error correction circuit, concealment circuit, oversampling filter, digital-to-analog (D/A) converters, and output filters.
The servo and control system, in addition to a display system, directs the mechanical operation of the CD player, such as the player""s spindle drive, and auto-tracking and auto-focusing functions. The servo, control and display system also directs the user interface to the CD player""s controls and displays.
A CD player uses a sophisticated optical read-out system to read data, control motor speed, track the pit spiral and adjust pickup positions and timings. While a spindle motor is used to rotate the disc with constant linear velocity, in another servo loop, information from the data itself determines correct rotating speed and data output rate.
User controls and their interface to the player""s circuitry is monitored by a microprocessor. A software program controls several modes of player operation. Subcode data is also used to direct the pickup to the proper disc location. For example, a time code is used to locate the start of any track.
Once data is recovered from the CD, the player must go through a series of activities to decode audio information in order to reconstruct an audio signal; namely, the EFM (eight-to-fourteen modulation) data is modulated, and errors are detected and corrected using an error correction algorithm. Additionally, using interpolation and muting, the audibility of gross errors is minimized.
Subsequent to decoding of the audio information, the digital data must be converted to a stereo analog signal. This conversion process requires one or two D/A converters and low-pass filters (in analog or digital domain).
An audio de-emphasis circuit exists in the audio output stages of CD every player. Some CDs are configured for improved signal-to-noise ratio. This configuration is accomplished by encoding the CD with an audio pre-emphasis flag in the subcode, where high frequencies on a master tape is slightly boosted (50/15 xcexcs characteristic). The result, on CD playback, is inverse attenuation of the disc""s high frequencies, because the player switches in the de-emphasis circuit when required, so that the signal-to-noise ratio is slightly improved.
The final output circuit is the buffer, which ensures that the CD player""s line level output is appropriate to drive necessary external amplifiers with a minimum amount of analog distortion.
With-respect to a player""s pickup design, a CD may contain as many as three billion pits, all orderly arranged on a spiral track. Each optical read-out system, which comprises an entire lens assembly and pickup, must focus, track and read data stored on a spiral track. The lens assembly, which is a combination of the laser beam and a reader, must be small enough to move across the underside of a disc in response to tracking information and user random-access programming. Moreover, movement of the pickup from a CD""s center to its edge must be focused despite adverse playing conditions, such as when a CD is dirty or vibrating.
Unlike an LP, which has grooves to guide the pickup, a CD has a singular spiral pit track running from a center circle to its outer edge. The only object that touches the disc surface is an intensity-modulated laser light, which carries data and which is susceptible to obstructions, such as vibrations. Four standard methods have been designed for tracking pit spiral: (1) one-beam push-pull; (2) one-beam differential phase detection; (3) one-beam high frequency wobble; and (4) three-beam.
The optical pickup must be precise in order to accommodate approximately 600,000 pits per second. Even the flattest disc is not perfectly flat; disc specifications acknowledge this by allowing for a vertical deflection of xc2x1600 xcexcm. In addition, a xc2x12 xcexcm tolerance is required for the laser beam to stay focused, otherwise the phase interference between directed and reflected light is lost, along with audio data, tracking and focusing information. Therefore, the objective lens must be able to re-focus while the disc""s surface deviates vertically.
An auto-focus system, driven by a servo motor, manages this deviation, using control electronics and a servo motor to drive the objective lens. Three techniques are available for generating a focusing signal: (1) a cylindrical lens using astigmatism; (2) a knife edge using Foucault focusing; and (3) critical angle focusing.
Any pickup must perform both tracking and focusing functions simultaneously. Therefore, a completed pickup design would use a combination of the above-mentioned auto-tracking and auto-focusing techniques. Two standard pickup designs stand out from the rest when auto-tracking and auto-focusing functions are combined: (1) one-beam push-pull tracking with Foucault focusing, (hereinafter xe2x80x9cone-beam pickupxe2x80x9d); and (2) three-beam tracking with astigmatic focusing, (hereinafter xe2x80x9cthree-beam pickupxe2x80x9d).
Both of these designs have been commercialized among manufacturers. One-beam pickups, which are usually mounted on a distal end of a pivoting arm, swings the pickup across a disc in an arc. On the other hand, three-beam pickups are mounted on a sled, which slides linearly across the disc.
The following exemplary prior art discussion will be limited to three-beam pickups only.
Prior Art FIG. 7 shows the optical path of a three-beam pickup, which uses a laser as the light source. A laser is used, rather than a bulb, for a number of reasons. First, a laser uses an optical resonator to stimulate atoms to a higher energy level that induces them to radiate in phase, a condition necessary to achieving sharper data surface focus and proper intensity modulation from the pit height.
Second, a laser light, unlike a bulb""s light, which radiates all the frequencies of a spectrum at all different phases, is composed of a single frequency and is coherent in phase. An important advantage of phase coherency is phase cancellation in the beam that is produced by disc pits, so that disc data can be read. Most CD pickups use an aluminum gallium arsenide semiconductor laser with a 0.5 milliwatt optical output that radiates a coherent-phase laser beam with a 780 nanometer wavelength; the beam is comprised of near-infrared light.
Referring to Prior Art FIG. 7, a laser diode is positioned adjacent the focal point of a collimator lens with a long focal distance, for the purpose of making the divergent light rays parallel. A monitor diode (not shown) is also placed adjacent the laser diode in order to control power to the laser. The monitor diode stabilizes the laser""s output in two important ways; first, by compensating for temperature changes so as to prevent thermal runaway; and second, by conducting current in proportion to the light output of the laser.
The three-beam pickup is so termed because it uses three beams for tracking and reading a CD. To generate these beams, a laser light first passes through a diffraction grating, which resembles a screen with evenly-spaced slits of a few laser wavelengths apart. As the beam passes through the grating, the light diffracts into fringes of parallel light beams. When the collection of these beams is re-focused, the collection appears as a single, bright centered beam with a series of successively less intense beams on either side of the center beam.
It is this diffraction pattern that actually strikes the CD, where the center beam is used for both reading data and focusing. In a three-beam pickup, two of the series of successively less intense beams, or two secondary beams, are used for tracking only. In a one-beam pickup, data reading, focusing and tracking is accomplished with just one beam.
Another element in the three-beam optical design is the polarization beam splitter, or PBS, which consists of two prisms having a common 45 degree facing that acts as a polarizing prism. The purpose of the PBS is to direct the laser light to the disc, and to angle the reflected light (from the disc) to the photosensor. In some designs, a half-silvered mirror is used.
In Prior Art FIG. 7, the collimator lens is shown as following the PBS, even though it can precede the PBS in other designs. Once the light exits the collimator lens, it then passes through a quarter-wave plate (QWP). The QWP is an anisotropic material that exhibits properties with different values when measured in different directions, so that when light passes through the QWP, it rotates the plane of polarization of each passing light beam. This rotation is required to make the PBS work.
The anisotropic quality of the quarter-wave plate is equally important to the process occurring on the right-hand side of the plate. Light passing through the QWP to the CD, will be reflected from the CD back again through the QWP and become polarized. More importantly, the light is polarized in a plane at right angles to that of the incident light.
In other words, the reflected polarized light re-entering the quarter-wave plate (from right to left) will pass through the collimator and strike the polarization beam splitter. Because the polarization beam splitter passes light in one plane only (e.g., horizontally) but reflects light in the other plane (e.g., vertically), the PBS will properly deflect the reflected beam toward the photodiode sensor to read the digital data.
The final optics element in the path to the CD is the objective lens. The objective lens is used to focus laser beams into a convergent cone of light onto the CD""s data surface, taking into account the refractive index of the polycarbonate substrate of the disc. Convergence is a function of the numerical aperture (NA) of the lens, with most pickups using an objective lens having an NA of about 0.5.
As mentioned earlier, the laser beam""s size on the outer surface of the CD""s transparent polycarbonate substrate is approximately 800 micrometers in diameter. Since the refractive index of the substrate is 1.55 and its thickness is 1.2 millimeters, the laser beam""s size is narrowed to 1.7 micrometers at the reflective surface, a size slightly wider than the pit width of 0.5 micrometer and comparable in width to the light""s wavelength.
When the laser beam strikes a land, (the smooth surface between two pits), light is almost totally reflected. When the light strikes a pit (viewed as a bump by the laser), diffraction and destructive interference cause less light to be reflected.
In short, all three intensity-modulated light beams pass through the objective lens, the QWP, collimator lens, and the PBS. Before hitting the photodiode, they pass through a singlet lens and a cylindrical lens.
In any optical pickup system, automatic focusing is an absolute prerequisite. Disc warpage and other irregularities causes vertical deflections in the CD""s data surface. Such movement would place the data out of the pickup""s depth of focus, essentially making it impossible for the pickup to distinguish between pit height and land phase differences.
The unique properties of astigmatism are used to achieve auto-focusing in a three-beam CD player. This is illustrated in Prior Art FIG. 8.
The cylindrical lens, (see Prior Art FIG. 7), which prefaces the photodiode array, detects an out-of-focus condition. The condition is directly related to the distance between the objective lens and the CD""s reflective surface. As this distance varies, the focal point changes, and the image projected by the cylindrical lens changes its shape. The inter-relationship of the above elements is illustrated in Prior Art FIG. 8.
Changes in an image on the photodiode generates a focus correction signal. For example, when the distance between the objective lens and the CD decreases, the image projected by the lens moves further from the cylindrical lens, and the pattern becomes elliptical. Conversely, when the distance between the objective lens and the CD increases, the image projected by all lenses (e.g., the objective lens, an intermediate convex lens and the cylindrical lens) moves closer to the lens. However, the elliptical pattern that is formed is now rotated 90 degrees from the first elliptical pattern.
In the third and final scenario, which is when the disc surface lies exactly at the focal point of the objective lens, the image reflected through the intermediate convex lens and cylindrical lens is unchanged, and a circular spot strikes the center of the photodiode.
An important aspect of the three-beam auto-focus system is correction voltages. A photodiode uses a laser beam""s intensity level to generate a focus correction voltage, which in turn generates a control signal. These electrical signals control the mechanical motion of a servo motor, which is responsible for moving the objective lens along an optical axis in response to any vertical disc motion. Servo-controlled movement of the objective lens during disc motion results in automatic focusing.
Prior Art FIG. 9 illustrates a typical servo motor used to move the objective lens in the optical path. The servo motor consists of a coil and magnet structure generally used in loudspeakers.
Operation of a CD player begins when a CD is first loaded into the player. Technically, an electrical control signal is sent into the optical pickup system, which causes the laser to turn on, and the objective lens to move vertically until a focus condition is reached.
Then, the auto-focusing system takes over, except if two negative situations occur. If no CD is detected, the automatic focusing system tries again, and cuts off if it fails to detect a CD again. If the auto-focus is inoperative, such as when the CD tray is open, the system pulls back the objective lens to prevent damage to the lens or CD. Otherwise, the automatic focusing system performs its operation smoothly by keeping the pickup properly positioned beneath the spinning disc, in effect maintaining focus to within a tolerance of approximately xc2x10.5 micrometers.
Currently, encryption for data media, such as DVDs, involves one key. It is a fairly simple 40-bit scheme. There is good authentication of the platform, which is performed by various key exchanges within the mechanisms between the source drive and the actual platform decrypting the data.
A content scrambling system (CSS) is included in every DVD player. CSS is a method of encrypting a disc that the information technology (IT) and.motion picture industries agreed upon. In order to be licensed to manufacture DVD players, a company is required to obey certain rules pertaining to the uses (and non-uses) that a platform can perform, as part of a license agreement.
While the present invention is not required to incorporate the CSS encryption system, it could be one level of encryption, if a multi-level encryption is employed. Audio information is generally encrypted prior to being burned into a disc, such as a CD. Hence, there is no plain text; encrypted information only is contained on a CD. So, if a user seeks to access information contained on the CD, whether for listening or copying purposes, the user would have to decrypt the data in order to hear sensible audio data.
In general, existing ideas in the field appear to bury authentication keys within encrypted information that is burned into the disc. Authentication keys are buried using various authentication processes, which verify that the platform devicexe2x80x94whether a computer, CD player, DVD player, or the likexe2x80x94is a licensed device and, consequently, obeys certain copyright rules. Eventually, the licensed device uncovers the buried authentication key(s) and decrypts the data contained on the disc. So, the system needs to find the key before being eligible for decrypting the audio data.
The following prior patents represent the state of the art of preventing unauthorized copying of data, and are all hereby incorporated by reference:
U.S. Pat. No. 4,811,325 to Sharples, Jr. et al. discloses high speed copying of audio programs on optical CDs. The master CD is encoded using Adaptive Delta Modulation (ADM).
U.S. Pat. No. 4,879,704 to Takaai et al. prevents copying of an optical dis. Data is stored in a record protected area and in a record unprotected area, where each such sector has a representative address that helps to determine whether the data is in the record protected area or in the record unprotected area. Only data from the record unprotected area with an appropriate address can be copied.
U.S. Pat. No. 4,937,679 to Ryan discloses a video recording and copy prevention system. The video signal includes a copy-protect signal. Designated detectors detect the presence of copy-protected signal(s) and inhibit copying of such signals. A video correlate enables one to playback a copy-protected program for viewing only and generates an inhibit signal to prevent copying of a copy-protected signal.
In U.S. Pat. No. 4,975,898 to Yoshida, an erasing program erases the non-rewritable portion so that it cannot be copied on a copy disc during unauthorized copying of an optical disc.
U.S. Pat. No. 5,319,735 to Preuss et al. uses a digital code signal embedded with the original audio signal. The digital code gets transferred to the copy disc.
In U.S. Pat. No. 5,412,718 to Narasimhalu et al., non-uniformities and their attributes in the storage medium is used as a unique signature. This signature is used to derive a key for encrypting the information on the storage medium. During copying, the signature gets mutated and the information cannot be decrypted. During authorized copying, the information is decrypted by generating a key from the signature of the distribution medium.
In U.S. Pat. No. 5,418,852 to Itami et al., data is stored in a user accessible area and in a user inaccessible area, which are both compared to determine the authenticity of the recording medium.
In U.S. Pat. No. 5,513,260 to Ryan, copy-protected CDs have authenticating signature recorded on them. An authentication signature is obtained by a deliberately induced radial position modulation giving an error voltage corresponding to the elliptical errors. When playing the CD, the signature causes the player to correctly decrypt the program whereas, when playing an unauthorized copy of the CD, the absence of the signature is detected and false data is generated and the player does not play.
U.S. Pat. No. 5,538,773 to Kondo discloses the recording of data together with a cipher key information for copy protection.
U.S. Pat. No. 5,570,339 to Nagano discloses a system that converts data to digital data, which is then FM modulated with key information to vary the widths of the pits at the time of recording. During reproduction, the data is read out and if the key information is determined to be missing, copying is prevented.
U.S. Pat. No. 5,608,717 to Ito et al. discloses a CD-ROM that has a character/graphic pattern for copy protection. Password and information on the position of the character/graphic pattern bearing area of the CD-ROM are stored beforehand in a memory included in the CD-ROM""s controller of the playback system. The CD-ROM controller, therefore, will have the means for deciphering the enciphered password. Data are modulated by the EFM modulation method into bits of predetermined width and height having values corresponding to the EFM.
U.S. Pat. No. 5,608,718 to Schiewe discloses an optical disc having shallow pits bearing an identification/logo/watermark. The lands and pits are of different lengths for identification/authorization purposes when copying a CD.
U.S. Pat. No. 5,636,276 to Brugger discloses the distribution of digital music with copyright protection. An encryption table is embedded in the music CD player and includes a decryption module that uses the encryption table for authorized playing of music/information.
U.S. Pat. No. 5,636,281 to Antonini discloses an authorized access that uses mingling of data elements of the program memory to be protected according to a secret order. To use this memory, a transcending device is used. The transcending device is in the form of a memory containing several tables, only one of which gives the right transcending data elements.
The problem with one or more of the above-mentioned conventional encryption/decryption systems is that a pirate or hacker seeking to hack into the encryption process on a disc could do so by playing the encrypted music, finding the decryption key, which is already buried, mixed and interleaved with the audio data or the encrypted audio data, and using that key to decrypt the audio on the disc.
In other words, accompaniment of the decryption key within the audio data lends itself to discovery, even if the audio data is played or transmitted in an encrypted form. A hacker could obtain decryption key(s) even if the encrypted audio data was placed onto an unlicensed computer platform having a DVD ROM drive that did not obey copyright protection rules. That is, if the audio is later played back, the key would be output along with the encrypted audio data.
An additional problem in one or more of the prior art references is that keys specific to, or derived from, the physical construction of the CD are not constructed or determined in a manner that is difficult to detect by a hacker. A further problem in the prior art is that the physical characteristics of the CD which are used to derive a key for authorized copying, are transferred in the audio and may be accessible to the hacker.
Yet another problem in one or more of the prior art references is that the solutions proposed therein require significant additional hardware and/or software to be implemented. That is, these prior art techniques do not take advantage of existing hardware/software within the CD or DVD player that can be used effectively to prevent unauthorized copying.
Yet another problem in one or more of the prior art references is that the solutions proposed therein are expensive, and incompatible with existing CD or DVD players. Hence, current solutions to unauthorized copying are difficult and impractical in their implementation.
Yet another problem in one or more of the prior art references is that the solutions proposed therein are limited to CD and/or DVD players, and do not consider or structure such techniques when data is transmitted from, to, and/or over local and/or global networks, such as the Internet.
It is a feature and advantage of the present invention to provide a method and/or apparatus for minimizing pirating of, or unauthorized access to, data on a data media that is inexpensive, and compatible with existing CD and/or DVD-players, and other forms of data recording and/or playing devices.
It is another feature and advantage of the present invention to provide a method and/or apparatus for minimizing pirating of, or unauthorized access to, data on a data media that is manageable and practical in its implementation.
It is another feature and advantage of the present invention to provide a method and/or apparatus for minimizing pirating of, or unauthorized access to, data on a data media that does not require significant additional hardware and/or software in its implementation.
It is another feature and advantage of the present invention to provide.a method and/or apparatus for minimizing pirating of, or unauthorized access to, data on a data media that uses and/or adapts existing hardware/software within, for example, the CD or DVD player that can be used effectively to prevent unauthorized copying.
It is another feature and advantage of the present invention to provide a method and/or apparatus for minimizing pirating of, or unauthorized access to, data on a data media that uses or creates data keys specific to, or derived from, the physical construction of the CD or other data disc in a manner that is difficult to detect by a hacker.
It is another feature and advantage of the present invention to provide a method and/or apparatus for minimizing pirating of, or unauthorized access to, data on a data media that uses the physical characteristics of the CD to derive a key for authorized copying, and which key is prevented from being transferred in the audio and, therefore, not accessible to the hacker.
The present invention relates to a method and system of preventing unauthorized copying of data on data media, including CDs and DVDs. Generally, an authorized CD is designed to require decoding by an authorized disc player. The authorized CD includes certain information used by an authorized CD player for playing music. An unauthorized copied CD, however, does not have the requisite encryption/decryption key(s) necessary for decoding.
Consequently, a feature and advantage of the present invention is to prevent piracy of audio and/or video data from data discs; that is, to provide greatly enhanced security measures against data disc pirating. The present invention is based, in part, on my discovery that the authorization key(s) need not necessarily be transferred in the audio using conventional hardware and/or software in, for example, CD or DVD players that may be adapted in one or more ways described below.
The above features and advantages are accomplished generally by making a physical mark on the media; a mark that would represent zeros and ones forming part of an authentication key or keys. Physical marking of the data media is manifested in three different methods; namely, via pit width modulation, pit depth modulation and/or pit track modulation.
Singular or multi-level decryption systems may be used for preventing unauthorized copying of audio data on a disc. Similarly, two or three different decryption systems, each of which successively must be decrypted before the audio is finally available, may also be used.
Advantageously, the present invention optionally uses three or four different sources for making or compiling a long or compound keys. Thus, in other words, instead of having a multi-layered decryption or authentication system, the present invention optionally includes a multi-level key, each component of which must be found in order to build the whole key to perform the entire authentication process.
According to the present invention, there are three ways that these authentication keys can be formed and remain hidden. Each method of producing authentication keys are a function of the physical characteristics of a disc that does not normally travel with the audio data. Each method generally makes a physical mark on the media representing zeros and ones, which form part of an authentication key. Moreover, the following three methods may be used individually and/or in combination to prevent piracy of audio and/or video data from discs, such as CDs, DVDs, and other data, discs.
The first method is pit width modulation, which requires, in the normal layers of a CD or DVD, a variation in the width of a pit. Variations preferably occur within normal manufacturing tolerances of 10 to 15 percent. A CD or DVD player would require an additional detector that would examine voltage irregularities resulting from width modulation.
Another method is pit depth modulation, by which variations in pit depth also preferably occur in a predetermined physical manner within normal manufacturing tolerances. According to this method, a disc player would not register a disc""s abnormal tolerances. The focus server, which focuses the layers contained on a disk, would supply a modulated voltage according to a pit depth modulation. The modulated voltage could then be used to obtain a key. For example, different predetermined modulated voltages may be indicative of different keys.
A third method is pit track modulation in which the smooth, continuous spiral is modulated on a very small level with data at low frequencies relative to the pit rate. It is also possible to modulate the spiral by looking at the modulation of the tracking server in a player. The data is then built with a part of the key. Here, modulation also occurs within normal manufacturing tolerances (e.g., xc2x110-15 percent) to avoid running the risk that existing players would not be able to track the disc successfully.
The advantage of using one or more of the above three physical methods of burying authentication key(s) on a disc is that it eliminates an obvious method that a pirate could use to reproduce discs. That is, a pirate will have to initially produce a disc that meets the physical predetermined requirements of the disc to be copied, before being able to copy therefrom.
For example, it is possible to get at the direct data output from a CD or DVD player before any of the demodulation processes occurs. This is accomplished using the RF or FM method, where the data stream is copied directly from one disc to another disc by going to a direct data input. Thus, actual audio data stored on a disc can be easily transferred, bit for bit or symbol for symbol, and copied onto another disc, because the data being copied is a function of the actual audio encrypted data screen; it is not a function of the pit width or track modulation.
The present invention, on the other hand, employs methods of producing authentication keys that are a function of the physical characteristics of a disc that do not travel with the audio data. The present invention configures the physical characteristics of a disc by essentially creating a predetermined modulation used to bury one of the authentication keys, which would not be transferred and which will not appear at the audio output. Thus, another disc having the same modulation characteristics is required in order for it to be considered an authenticated CD or data disc.
Accordingly, the present invention utilizes a process that creates various depths or widths, for example, of pits in a disc within predetermined tolerances to generate an authentication key or keys in validating whether the disc (and/or data) is authentic and, therefore, proper to record thereon. Various standard processes may be used to impregnate, implant, form or configure the disc to include the predetermined pit depth, width or track modulation or variation with the desired tolerances.
Another feature of the present invention is the combinative use of the above three methods for either generating a security authentication key having two or more components, or for accessing the key buried in different places on the disc. For example, a single authentication key may comprise the combination of components generated by using the pit width, pit track and pit depth modulation methods.
Alternatively, one method, such as pit width modulation, may generate an authentication key that indicates a random location on the disc where a second authentication key or code is located, and so forth. That is, one method may be used as an address pointer, which may be programmed into the table-of-contents area on a disc.
Yet another alternative involves using one method, such as pit width modulation, to generate an authentication key or code that validates a second key/code, which can be generated using a different modulation method, such as pit track modulation. Additional keys and/or components may also be generated or used.
To achieve these and other objects, the present invention provides a computer program product that stores computer instructions thereon for instructing a computer to perform a process of authenticating a data media, such as a CD or DVD, as fraudulent/pirated or non-fraudulent.
In accordance with one embodiment of the invention, a method authenticates at least one of a media and data stored on the media in order to prevent at least one of piracy, unauthorized access and unauthorized copying of the data stored on the media. At least one pit depth, pit width or pit track modulated data, derived from a physical characteristic of a data disc, is introduced with the original data resulting in mixed data. The mixed data is optionally stored on the media. Each pit depth and/or pit width and/or pit track modulated data includes at least one authentication key or at least one component of an authentication key, for authenticating whether the media and/or data is authorized.
The method includes the following sequential, non-sequential and/or sequence independent steps: (a) reading mixed data from a media; (b) detecting at least one of pit depth, pit width and pit track modulated data from the mixed data; (c) comparing each pit modulated data to at least one authentication key or component thereof; (d) authenticating at least one of the media and the pit modulated data in the mixed data responsive to the comparing (c) step; (e) removing pit modulated data from the mixed data via a decoding operation resulting in substantially unimpaired corrected data; and (f) outputting the unimpaired corrected data as at least one of audio, video, audio data, video data and digital data substantially free of pit modulated data.
The method also includes the steps of: (g) physically altering at least one of a pit depth, pit width and pit track of a data disc on at least one of a per track basis and on an interval basis throughout the data disc such that authentication is performed for at least one of each track to be played, throughout playback and throughout recording; (h) using a process defined in at least one of the reading, detecting, comparing, authenticating, removing and outputting steps, as a multi-level authentication system containing at least two different authentication keys, each of which successively must be authenticated before said unimpaired corrected data is finally output; and (i) performing the method of authenticating over a plurality of interconnected computer networks comprising at least one of a local network, global network and Internet.
In accordance with another embodiment of the invention, a data player includes a data processor performing the steps of: (a) reading mixed data from the media; (b) detecting at least one of pit depth, pit width and pit track modulated data from the mixed data; and (c) comparing each pit modulated data to at least one authentication key or component thereof. The data player authenticates the media and/or the pit depth, pit width and/or pit track modulated data in the mixed data responsive to the comparing, and removes the pit modulated data from the mixed data resulting in substantially unimpaired corrected data. The data player outputs the data as at least one of audio, video, audio data, video data and digital data substantially free of pit modulated data.
According to another embodiment of the invention, a data message comprises at least one authentication key formed by modulating at least one of a disc pit, width and track on a basis of a physical characteristic of said disc. The pit modulated data is combined with the original data to form mixed data that is introduced into the data message. Each pit modulated data comprises at least one authentication key or component thereof used in authenticating whether the data message is authorized. The pit depth, pit width or pit track modulated data cannot be readily altered, obscured or removed from the mixed data without simultaneously degrading or impairing a quality of an audible component of the data message. The data message is advantageously transmitted substantially free of each pit modulated data, preventing a destination processor from reading and subsequently authenticating the data message.
According to another embodiment of the invention, a data disc comprises at least one variation, based on a physical characteristic of the disc, in the disc""s pit width, pit depth and/or pit track. The pit depth, width and/or track modulated data is introduced with original data resulting into mixed data. The mixed data stored on the data disc. Each pit modulated data, which comprises at least one authentication key or component thereof, is used in authenticating whether at the media and/or pit modulated data is authorized.
A computer or processor driven system, tangible medium including instructions thereon, and process is also provided.
There has thus been outlined, rather broadly, the important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will perform the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purposes of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be used as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
Further, the purpose of the foregoing abstract is to enable the U. S. Patent and Trademark Office and the public, generally, and especially scientists, engineers and practitioners in the art, who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection, the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
The above objects of the invention, together with other apparent objects of the invention, along with the various features of novelty that characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter, which illustrate preferred embodiments of the invention.